From the Guidelines
The most appropriate next step in the diagnostic workup for this 24-year-old woman with chronic abdominal pain and diarrhea would be to order serologic testing for celiac disease, including tissue transglutaminase antibody (tTG-IgA) and total IgA levels, while simultaneously obtaining a complete blood count, comprehensive metabolic panel, C-reactive protein, and fecal calprotectin, as recommended by the British Society of Gastroenterology guidelines 1.
This approach is supported by the guidelines for the investigation of chronic diarrhoea in adults, which recommend an initial screening blood test and stool tests for inflammation, including faecal calprotectin 1. Additionally, the guidelines for best practices in monitoring established coeliac disease in adult patients emphasize the importance of serology, including TG2Ab, in the diagnosis of coeliac disease 1.
The patient's symptoms, which started after a Caribbean cruise, could suggest a variety of potential causes, including infectious or dietary triggers. However, given the chronic nature of her symptoms, it is essential to rule out underlying conditions such as celiac disease or inflammatory bowel disease (IBD).
Key points to consider in the diagnostic workup include:
- Maintaining the patient on a gluten-containing diet before celiac testing to avoid false-negative results
- Using fecal calprotectin as a marker of inflammation to guide further testing, such as colonoscopy with biopsies if elevated or other inflammatory markers are abnormal
- Considering additional tests, such as stool studies to rule out infectious causes and a food diary to identify potential dietary triggers
By following this approach, clinicians can efficiently evaluate both celiac disease and IBD, which present with overlapping symptoms but require different management strategies, and provide the best possible outcome for the patient in terms of morbidity, mortality, and quality of life.
From the Research
Diagnostic Approach
The patient's symptoms of chronic abdominal pain and diarrhea, suspected to be related to conditions such as celiac disease or inflammatory bowel disease (IBD), require a thorough diagnostic workup.
Initial Diagnostic Tests
Based on guidelines and evidence from studies 2, 3, 4, 5, 6, the most appropriate next step in the diagnostic workup would be to conduct non-invasive tests to assess the presence of inflammation and rule out other potential causes.
- Celiac serologies to check for celiac disease
- Fecal calprotectin to assess the level of inflammation in the bowel
- C-reactive protein (CRP) to evaluate the level of systemic inflammation
Rationale
These tests are recommended because:
- Fecal calprotectin has been shown to be a reliable marker of intestinal inflammation, with high sensitivity and specificity for detecting IBD 2, 3, 4, 5.
- CRP is a useful biomarker for assessing systemic inflammation, although its sensitivity and specificity for IBD are lower than those of fecal calprotectin 5, 6.
- Celiac serologies are essential for diagnosing celiac disease, which can present with similar symptoms to IBD.
Further Testing
If the initial tests suggest the presence of IBD or celiac disease, further testing such as colonoscopy with ileoscopy and biopsies may be necessary to confirm the diagnosis and assess the extent of disease. However, based on the provided evidence, the initial step would be to conduct the non-invasive tests mentioned above.
Considerations
It is essential to consider the patient's clinical context, medical history, and symptoms when interpreting the results of these tests. A comprehensive diagnostic approach, including a combination of clinical evaluation, laboratory tests, and imaging studies, is necessary to establish an accurate diagnosis and develop an effective treatment plan.